Process for oxidation of 4-nitroso-m-cresol

ABSTRACT

The invention provides an oxidation process for converting 4nitroso-m-cresol to the corresponding 4-nitro-m-cresol by reacting the nitroso compound with an oxidizing agent in the presence of a catalyst at reflux temperatures in a reaction solvent solution including lower aliphatic and alicyclic ketones. The mixture thereafter is cooled and the 4-nitro-m-cresol is recovered from the solvent solution.

United States Patent 11 1 Baldwin et al.

1 1 Sept. 25, 11973 PROCESS FOR OXIDATION OF 4-NITROSO-M-CRESOL [75]Inventors: Roger A. Baldwin, Oklahoma City,

Okla.; Ming T. Cheng, Buena Park, Calif.

[73] Assignee: Kerr-McGee Corporation,

Oklahoma City, Okla.

[22] Filed: June 3, 197.0

[2]] Appl. No.: 43,225

FOREIGN PATENTS OR APPLICATIONS 8,256 3/1968 Japan 260/622 R OTHERPUBLICATIONS Wallace Hydrogen Peroxide in Organic Chemistry" pp. 25,26and 52 OD 281 09 W 34 Ber. Vol. 71, Kuhn et al. pp. 779-780 Webster'sNew Internat. Dictionary Sec. Ed. 1940) p. 1221 Groggins Unit Processesin Organic Synthesis" (1958) pp. 493-494 & 497499 PrimaryExaminer-Bernard Helfin Assistant ExaminerW. B. Lone Att0rneyWilliam G.Addison [5 7] ABSTRACT The invention provides an oxidation process forconverting 4-nitroso-mcresol to the corresponding 4- nitro-m-cresol byreacting the nitroso compound with an oxidizing agent in the presence ofa catalyst at reflux temperatures in a reaction solvent solutionincluding lower aliphatic and alicyclic ketones. The mixture thereafteris cooled and the 4-nitro-m-cresol is recovered from the solventsolution.

6 Claims, No Drawings PROCESS FOR OXIDATION OF- 4-NITROSO-M-CRESOLBACKGROUND OF THE INVENTION Nitrophenolic compounds are useful asindicators as well as intermediates for many valuable materials and areparticularly suitable for use in the preparation of insecticidecompounds such as 0,0-diethyl-O-(4- nitrophenyl) phosphorthioate(commonly known as ethyl parathion) and 0,0-dimethyl--(3-methyl-4-nitrophenyl) phosphorthioate. Heretofore, it has been suggested toprepare such nitrophenolic compounds via the nitration of phenolicmaterials with sulfuricnitric acid mixtures. Such nitrations are knownto give a variety of isomers, usually in low yield, accompanied byconsiderable quantities of tars and colored materials. Such by-productsresult from the oxidation of the phenolic starting materials.

It has also been suggested to prepare nitrophenolic compounds by thecaustic hydrolysis of chloronitroaromatic derivatives. The use of suchcaustic hydrolysis suffers from the disadvantage, however, that it isdifficult to obtain the desired isomer required for the hydrolysiswithout the formation of unwanted isomers which must be removed from themixture. Thus, nitration of chlorobenzene, a well known procedure,yields about a 65/35 mixture of the paraand ortho-isomers ofchloronitrobenzene. Subsequent caustic hydrolysis of this mixture yieldsthe corresponding orthoand para-nitrophenols. However,since.ortho-nitrophenol is inactive in insecticides such as methyl andethyl parathion, it must be removed from the mixture before thepara-nitrophenol can be used in insecticide manufacture.

It has also been suggested that nitrophenolic compounds can be preparedby oxidizing the corresponding nitroso compound. In fact, inHollingsworth, R. M., Biochemical Factors Determining Selective Toxicityof the Insecticide Sumithion and Its Analogs, PhD. Thesis, University ofCalifornia, Riverside, 1966, p. 55, it is suggested to effect theoxidation of 4-nitroso-mcresol compounds utilizing dilute nitric acid,i.e., one volume of concentrated nitric acid for three volumes of water.That process is described as being carried out at 40C. for l A hours;however, it produces a product in a yield of only about 31.5 percent.

Another process which has been suggested utilizes 30 percent hydrogenperoxide as an oxidizing agent, the reaction being carried out inglacial acetic acid and with catalytic amounts of ammonium molybdate. Ithas been found that when using d-nitroso-m-cresol, the resultantreaction mixture must be heated briefly to initiate the reaction. Afterworkup, which includes dilution with water followed by extraction withether, yields of only about 60 percent of the 4-nitro-m-cresol areobtained.

Thus, while these prior art processes provide satisfactory products,they are not completely satisfactory commercially because of therelatively low yields obtained.

SUMMARY OF THE INVENTION The surprising discovery now has been made that4- nitroso-m-cresol may be oxidized to the corresponding nitrophenoliccompound in exceptionally high yields by effecting the oxidation atreflux temperatures utilizing hydrogen peroxide as the oxidizing agent,ammonium molybdate as a catalyst and lower aliphatic or alicyclicketones as the reaction solvent. The reason that higher yields areobtained using these solvents in place of glacial acetic acid is notfully understood at the present time. However, when such solvents areused, yields in excess of percent consistently have been obtained.

It has been found that the amount of hydrogen peroxide used may varywithin relatively wide limits. However, amounts at least 5 percent inexcess of the stoichiometric amount, based on the initial quantity ofnitroso compound, must be used. Amounts up even as high as 60 percentmay be used although no advantages are obtained using such largeexcesses. A preferred range is an excess of about 5-20 percent.Particularly satisfactory results have been obtained using 30 percenthydrogen peroxide of commerce.

An example of a catalyst which has been found to be suitable in theprocess of this invention is ammonium molybdate, (NHUGMO O 4-4I-I O.Other suitable catalysts include sodium tungstate and sodium molybdate.Ferrous salts do not catalyze this oxidation reaction.

Solvents which are suitable for use in the preferred reaction compriselower aliphatic or alicyclic ketones in which the nitrophenolic productis soluble. Particularly satisfactory results have been obtained usingacetone and methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone,diisobutyl ketone, methly isopropyl ketone, cyclohexanone, methlycyclohexanones, cyclopentanone, methly cyclopentanones and the like.

As indicated hereinabove, the reaction is carried out at the refluxtemperature of the reaction mixture. The time of the reaction appears tobe critical. Thus, it has been found that the mixture must be maintainedat the reflux temperature for at least 2 hours to obtain the desirednitrophenolic compounds in high yields. If, for example, the reaction iscarried out for less than 1 hour, the reaction does not go tocompletion. The exceptionally high yields obtainable by practice of thisinvention are obtainable only when the reaction is carried out for 2hours or longer.

Generally, only relatively small quantities of catalyst need beemployed, that is, about 1 to 3 grams of catalyst per mole of nitrosocompound. Greater amounts of catalyst may be used if desired; however,this only increases the cost of performing the reaction withoutincreasing the yield or purity of product obtained.

DESCRIPTION OF PREFERRED EMBODIMENTS To illustrate the invention evenmore fully, the following specific examples are set forth. It will beunderstood, of course, that these examples are only illustrative and donot limit the scope of the invention which is defined in the appendedclaims.

EXAMPLE I A solution consisting of 55.5 grams (0.405 moles) of4-nitroso-m-cresol and 2.5 grams (0.002 moles) of ammonium molybdatecatalyst dissolved in 500 ml of acetone is heated to reflux and therethen is added to the solution over a period of about 1 hour, 66 ml (0.64moles) of 30 percent hydrogen peroxide. The resulting mixture iscontinuously maintained at the reflux temperature for a period of about5 hours, after which the mixture is cooled and the acetone solventrecovered at reduced pressure. The red-orange solids remaining arewashed thoroughly with water until the washes no longer test forperoxide. The resulting tan powder is dried and weighs 59.7 grams with amelting point of l25-l28C. The yield is 93 percent.

bromide pellets) of each sample is obtained and is compared with knownreference mixtures. Pertinent data presented in Table I show that thereaction is substan- EXAMPLE 2 tially complete after 2 hours. To agently refluxing solution of 6.8 g (0.049 moles) 5 TABLE 1 of4-nitroso-m-cresol and 0.1 g (8.0 X moles) of mmonum mol bdate catal stin ml methl eth 1 Ram ox'damn of a l y y y y 4-Nitroso-m-Cre11ol ketonesolvent 1s slowly added a solut1on of4 ml (0.078 Sample Melting PointRange, C Melting Point llangc moles) of 30 percent hydrogen peroxide.After five l0 ff hours at the reflux temperature, the solvent iscarefully 1 Melts 122425. mm, 11 Ni"o/5% removed at reduced pressure.The resulting solid prodg z g uct is washed with dilute sodium sulfitesolution until 12234265 all excess peroxide is destroyed. After furtherwashing, 2 hrs. Melts 125-1275, softens 123 QBfi-Nitrofithe4-nitro-m-cresol product obtained weighs 6.6 g and 15 gi s the yleld 1s91.4 percent. 126-127 6 hrs. Melts l26l27.5, softens 123 EXAMPLE 3Similarly, examination of the infrared spectra of the A solution of 13.7g (0.1 mole) of 4-nitroso-m-cresol above samples at about 1,035 cm andat 1,020 cm and 1 ml of 10 percent ferrous sulfate solution in 60 ml 20reveals the oxidation is about 98 percent complete of acetone is warmedto the reflux temperature. To this after 2 hours and is even morecomplete after 6 hours. solution is added 15 ml of 30 percent hydrogenperox- Additional examples of this invention are given in ide (0.12mole) after which the mixture is heated at re- Table II.

TABLE 11 Moles Reaction Product Example 4-11itroso- Ammonium Aco-Reaction time, yield Product No. 1n-cresol molybdate 30% H1O;to11e,111l. ten1p., C. l1r. percent M.P., C

0. 084 0. 0004 0. 137 53. 5 125-127 0. 010 0. 00024 0. 07s 01. 3 140-1500. 010 0.00 0. 078 H. 165-167 0. 040 0. 00021 0. 07x 23. 5 122-124 0.040 0. 0002-1 0. 07s 00. 0 125-127 0. 040 0. 0000s 0. 030 87. s -110 0.40.1 0. 0020 0. 04s 03. 0 125-125 0. 100 0. 00010 0. 120 80. 0 125-1230. 100 0. 00010 0. 0. 100 0.00008 0. 0.100 0.00016 0.105 0. 100 0. 000120. 110 0.100 0. 00010 0.105 1.000 0. 00323 1.55 0. 755 0. 00061 0. 8750. 200 0. 00032 0.2 0.1 0.12 1.123 0. 0008 1.41 1.0 0. 0032 1.5 0.00101.01

1 1001111. g1. acetic acid.

I 60 1111. g]. acetic acid.

3 Minutes.

4 1 ml. of 10% FeClz solution.

flux for 4 hours. The solvent is removed, the residue washed carefullyto remove peroxide values, and air dried. The residue is largelyunoxidized 4-nitroso-mcresol, demonstrating that ferrous sulfate is nota satisfactory catalyst in the process of this invention.

EXAMPLE 4 The results set forth in Table II show that: in Example 5, theuse of glacial acetic acid results in a low product yield; in Example 6,that the product is of indeterminate character and appeared to belargely unreacted starting material as shown by the relatively high andbroad melting point range; in Example 7, that the absence of catalystresults in a quantitative recovery of staring material as shown by thehigh but narrow melting point range; in Example 10, use of less than astoichiometric amount of oxidant results in product containingunoxidized nitroso compound; in Example 21 that FeCl, also is not asatisfactory catalyst; in Examples 22 and 24, that an insufficientamount of catalyst was employed.

What is claimed is:

1. A process for oxidizing 4-nitroso-m-cresol to form 4-nitro-m-cresolwhich comprises: heating a mixture of 4-nitroso-m-cresol and hydrogenperoxide in a reaction solvent in the presence of a catalyst to thereflux temperature of the mixture; maintaining said temperature for atime of at least 2 hours to effect oxidation of the 4-nitroso-m-cresolto 4-nitro-m-cresol and recovering the 4-nitro-m-cresol from themixture; said solvent being selected from the group consisting of loweraliphatic and alicyclic ketones in which the 4-nitro-mcresol is soluble;said catalyst being selected from the group consisting of ammoniummolybdate, sodium molybdate and sodium tungstate and said hydrogenperoxide being present in an amount of at least 5% in excess of thestoichiometric amount required to oxidize the 4- nitroso-m-cresol.

2. A process as set forth in claim 1 wherein the 4- nitroso-m-cresol andcatalyst are mixed in said solvent, heated to reflux temperature andmaintained at said temperature while the hydrogen peroxide isintroduced.

3. A process as set forth in claim 1 wherein the catalyst is ammoniummolybdate.

4. A process for oxidizing 4-nitroso-m-cresol to form 4-nitro-m-cresolwhich comprises: heating a mixture of 4-nitroso-m-cresol and hydrogenperoxide in a reaction solvent in the presence of a catalyst to thereflux temperature of the mixture; maintaining said temperature for atime of at least 2 hours to effect oxidation of the 4-nitroso-m-cresolto 4-nitro-m-cresol and recovering the 4-nitro-m-cresol from themixture; said catalyst being selected from the group consisting ofammonium molybdate, sodium molybdate and sodium tungstate; said hydrogenperoxide being present in an amount of at least 5% in excess of thestoichiometric amount required to oxidize the 4-nitroso-m-cresol andsaid solvent being selected from the group consisting of acetone, methylethyl ketone, diethyl ketone, methyl isobutyl ketone, di-isobutylketone, methyl isopropyl ketone, cyclohexanone, methyl cyclohexanone,cyclopentanone and methyl cyclopentanone.

5. The process of claim 41 wherein the solvent is selected from thegroup consisting of acetone and methyl ethyl ketone.

6. A process as set forth in claim 4 wherein the 4- nitroso-m-cresol andcatalyst are mixed in said solvent, heated to reflux temperature andmaintained at said temperature while the hydrogen peroxide is intro-UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No.3,761,527 Dated sept m r s, 1975 Inventor) Roger A. Baldwin and Ming T.Cheng It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

In the heading, Assignee should read Kerr-McGee Chemical Corp.

Signed and sealed this l9th day of November 1974.,

(SEAL) Attest:

McCOY M. GIBSON JR. 0. MARSHALL DANN Attesting. Officer Commissioner ofPatents USCOMM-DC 6037 6-P69 f1 u.s'. GOVERNMENT PRINTING OFFICE: L9690-366-33- FORM PC4050 (10-69)

2. A process as set forth in claim 1 wherein the 4-nitroso-m-cresol andcatalyst are mixed in said solvent, heated to reflux temperature andmaintained at said temperature while the hydrogen peroxide isintroduced.
 3. A process as set forth in claim 1 wherein the catalyst isammonium molybdate.
 4. A process for oxidizing 4-nitroso-m-cresol toform 4-nitro-m-cresol which comprises: heating a mixture of4-nitroso-m-cresol and hydrogen peroxide in a reaction solvent in thepresence of a catalyst to the reflux temperature of the mixture;maintaining said temperature for a time of at least 2 hours to effectoxidation of the 4-nitroso-m-cresol to 4-nitro-m-cresol and recoveringthe 4-nitro-m-cresol from the mixture; said catalyst being selected fromthe group consisting of ammonium molybdate, sodium molybdate and sodiumtungstate; said hydrogen peroxide being present in an amount of at least5% in excess of the stoichiometric amount required to oxidize the4-nitroso-m-cresol and said solvent being selected from the groupconsisting of acetone, methyl ethyl ketone, diethyl ketone, methylisobutyl ketone, di-isobutyl ketone, methyl isopropyl ketone,cyclohexanone, methyl cyclohexanone, cyclo-pentanone and methylcyclopentanone.
 5. The process of claim 4 wherein the solvent isselected from the group consisting of acetone and methyl ethyl ketone.6. A process as set forth in claim 4 wherein the 4-nitroso-m-cresol andcatalyst are mixed in said solvent, heated to reflux temperature andmaintained at said temperature while the hydrogen peroxide isintroduced.